Yes, there were signs that Ebola was in west Africa, perhaps as far back as 1973...

If a bat carries Ebola virus in the forest, people find signs of infection in humans, publish it and read about it, but no-one remembers, does it make a sound?

Apparently, it now does. The New York times [3] has found that there were studies reporting signs of Ebola virus antibodies in humans in Liberia in samples collected back in 1982.

I'll see your 1982 and raise you 1973! [1] That's when some other samples were collected that were found to contain antibodies to Ebola virus. This doesn't come up in the abstract for this article, but is buried in the Methods and Materials section.

"..antibodies specific for Marburg virus and Ebola virus antigens tested by immunoblotting (21% and 14%,respectively)"

We noted this paper in 2014 - in a piece for the Conversation [2] - and listed some other articles which found similar signs of prior human exposure to Ebola virus or something related. The NYT piece has also captured some of these papers by the looks of it.

In many (most?) cases, these scientific papers can only be reached after paying a fee, or being affiliated with an Institutions that has a good library. Many researchers, clinicians and public health professionals can be described as such.

For me, it seems clear that there were many people aware of the possibility the Ebola virus was pretty much "always" (in the context of our history with Ebola virus disease[EVD]) in the forests within the regions underneath the flyways of some likely filovirus-host bat species.

But seemingly no action was taken on these reports. Was that because...

• the serology assays were perhaps too non-specific or otherwise unreliable (were they cross-reacting with as-yet unknown filoviruses perhaps (h/t Stephen Goldstein)
• no-one thought much of EVD's capacity to cause a big outbreak? 
• we didn't care about smaller outbreaks because they had always been controlled previously?
• we just didn't care because it was "over there" (in Africa)?
• we just forgot about it as soon as it was published?

It really doesn't matter what the reason(s) was, because global political willingness to invest the mental and physical capital in a program that could think about, monitor and foresee the risks associated with anything found, and one with a very long view of protecting the public from possible infectious threats...just does not exist. 

This is not a problem specific to EVD of course. Trying to stay ahead of infectious threats will take much more devotion than the world has shown it can muster to date. Even when we can see their potential for harm, there are only so many resources we will mobilize for an infectious threat that is not knocking on our specific door.

References...

1. Neppert J, G�hring S, Schneider W, Wernet P.
   No evidence of LAV infection in the Republic of Liberia, West Africa, in the year 1973.
   http://www.ncbi.nlm.nih.gov/pubmed/3015288
2. How Ebola started, spread and spiralled out of control
   https://theconversation.com/how-ebola-started-spread-and-spiralled-out-of-control-32137
3. Yes, We Were Warned About Ebola
   http://www.nytimes.com/2015/04/08/opinion/yes-we-were-warned-about-ebola.html